Brilliant combination with their bass trombone case,
This review is from: Pro Tec Bass Trombone Mute Gig Bag 402
Before I had these two bags/cases, I went to band practices with my unnecessarily large and heavy Vincent Bach case and a large (open) bag containing mutes [H&B bucket (9.5"), rubber plunger, metal cup & straight], music, and trombone and music stands.
This bag easily takes my 4 mutes, and would certainly take one more. The side pocket will hold plenty of music.
More at the review for the case - Protec PB309CT Contoured Bass Trombone Pro Pac Case - Black